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Computing the language involves computing the source files, which is an expensive operation. It requires calling cmMakefile::GetOrCreateSource many times, which involves creating and matching on many cmSourceFileLocation objects. Source files of a target may depend on the head-target and the config as of commit e6971df6 (cmTarget: Make the source files depend on the config., 2014-02-13). The results are cached for each context as of commit c5b26f3b (cmTarget: Cache the cmSourceFiles in GetSourceFiles., 2014-04-05). Each target in the build graph causes language computation of all of its dependents with itself as the head-target. This means that for 'core' libraries on which everything depends, the source files are computed once for every transitive target-level-dependee and the result is not cached because the head-target is different. This was observed in the VTK buildsystem. Short circuit the computation for targets which have a source-list that is independent of the head-target. If the source-list has already been computed and the generator expression evaluation reports that it was context-independent, return the only source-list already cached for the target. Reset the short-circuit logic when sources are added and when the link libraries are re-computed.
CMake ***** Introduction ============ CMake is a cross-platform, open-source build system generator. For full documentation visit the `CMake Home Page`_ and the `CMake Documentation Page`_. .. _`CMake Home Page`: http://www.cmake.org .. _`CMake Documentation Page`: http://www.cmake.org/cmake/help/documentation.html CMake is maintained by `Kitware, Inc.`_ and developed in collaboration with a productive community of contributors. .. _`Kitware, Inc.`: http://www.kitware.com License ======= CMake is distributed under the OSI-approved BSD 3-clause License. See `Copyright.txt`_ for details. .. _`Copyright.txt`: Copyright.txt Building CMake ============== Supported Platforms ------------------- MS Windows, Mac OS X, Linux, FreeBSD, Solaris, HP-UX, IRIX, BeOS, QNX Other UNIX-like operating systems may work too out of the box, if not it should not be a major problem to port CMake to this platform. Subscribe and post to the `CMake Users List`_ to ask if others have had experience with the platform. .. _`CMake Users List`: http://www.cmake.org/mailman/listinfo/cmake Building CMake from Scratch --------------------------- UNIX/Mac OSX/MinGW/MSYS/Cygwin ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ You need to have a compiler and a make installed. Run the ``bootstrap`` script you find the in the source directory of CMake. You can use the ``--help`` option to see the supported options. You may use the ``--prefix=<install_prefix>`` option to specify a custom installation directory for CMake. You can run the ``bootstrap`` script from within the CMake source directory or any other build directory of your choice. Once this has finished successfully, run ``make`` and ``make install``. In summary:: $ ./bootstrap && make && make install Windows ^^^^^^^ You need to download and install a binary release of CMake in order to build CMake. You can get these releases from the `CMake Download Page`_ . Then proceed with the instructions below. .. _`CMake Download Page`: http://www.cmake.org/cmake/resources/software.html Building CMake with CMake ------------------------- You can build CMake as any other project with a CMake-based build system: run the installed CMake on the sources of this CMake with your preferred options and generators. Then build it and install it. For instructions how to do this, see documentation on `Running CMake`_. .. _`Running CMake`: http://www.cmake.org/cmake/help/runningcmake.html Contributing ============ See `CONTRIBUTING.rst`_ for instructions to contribute. .. _`CONTRIBUTING.rst`: CONTRIBUTING.rst